1. Field of the invention
The invention relates generally to polymer extrudates and, more particularly, to a method and apparatus for enhancing an extruded substrate with a decorative laminating film.
2. Description of the Related Art
Extrusion equipment is used to manufacture numerous items from thermoplastic resins including, for example, building materials and window coverings. Typical building materials include pipes, floor tiles, and wall members. Typical window coverings include horizontal louvers and vertical slats. In many cases, it is commercially desirable to decoratively enhance one or more surfaces of the extruded article so that is has a desire texture, color, or both. The methods used to date, however, are unsatisfactory from one or more points of view.
For example, in U.S. Pat. No. 4,877,077 that issued to George W. Ebert on Oct. 31, 1989 and is entitled VERTICAL COEXTRUDED PEARLESCENT LOUVER FOR VERTICAL BLINDS, a vertical slat having co-extruded layers is disclosed. The ""077 patent, in more detail, discloses a decoratively enhanced louver wherein an opaque substrate is co-extruded with a pearlescent layer. The ""077 structure is aesthetically pleasing, but relatively complicated to manufacture because of the co-extrusion requirements. Also, it takes a relatively long period of time to switch over from one color to another, it being necessary to completely reload the extrusion equipment.
There remains a need, therefore, for a method and apparatus which efficiently and cost effectively provides a decoratively enhanced substrate and, more particularly, does so without need for complicated co-extrusion techniques.
In a first aspect, the invention may be regarded as a method of decoratively enhancing an extruded substrate comprising: providing an extrusion die; heating a first polymer based composition to create a melt; forcing the melt through the extrusion die to form an extruded substrate; providing first and second rollers that are wider than the extruded substrate, the first and second rollers closely adjacent to one another to form a pinch point between the first and second rollers; providing a supply of decorative laminating film having a lamination substrate that is formed from a second polymer based composition; guiding the extruded substrate through the pinch point between the first and second rollers; guiding the preheated decorative laminating film through the pinch point between the first and second rollers in contact with the extruded substrate, the pinch point having a pressure profile across it width that has a relatively high pressure across a central portion of its width that is occupied by the extruded substrate and a relatively low pressure at edge portions on either side of the central portion that are not occupied by the extruded substrate; heating the first roller to a temperature sufficient to fuse a central length of the decorative laminating film to the extruded substrate when subjected to the relatively high pressure across the central portion without melting scrap side lengths of the decorative laminating film that are subjected only to the relatively low pressure at the edge portions of the pinch point; and peeling away the scrap side lengths of the decorative laminating film while leaving the central length of the decorative laminating film fused to the extruded substrate to decoratively enhance the extruded substrate.
In a second aspect, the invention may be regarded as an apparatus for decoratively enhancing an extruded substrate comprising: an extrusion die; means for heating a first polymer based composition to create a melt; means for forcing the melt through the extrusion die to form an extruded substrate; a first roller wider than the extruded substrate; a second roller wider than the extruded substrate, the second roller closely adjacent to the first roller to form a pinch point between the first and second rollers; the first and second rollers adjacent to the extrusion die to continuously receive the extruded substrate in the pinch point; a supply reel of decorative laminating film having a lamination substrate that is formed from a second polymer based composition; means for preheating the decorative laminating film to a first temperature which is below a melting point of the decorative laminating film at ambient pressure; means for guiding the preheated decorative laminating film through the pinch point between the first and second rollers in contact with the extruded substrate; the pinch point having a pressure profile across it width that has a relatively high pressure across a central portion of its width that is occupied by the extruded substrate and a relatively low pressure at edge portions on either side of the central portion that are not occupied by the extruded substrate; means for heating the first roller to a second higher temperature sufficient to fuse a central length of the decorative laminating film to the extruded substrate when subjected to the relatively high pressure across the central portion without melting scrap side lengths of the decorative laminating film that are subjected only to the relatively low pressure at the edge portions of the pinch point; and means for peeling away the scrap side lengths of the decorative laminating film while leaving the central length of the decorative laminating film fused to the extruded substrate to decoratively enhance the extruded substrate.
In a third aspect, the invention comprises a method of decoratively enhancing an extruded substrate comprising the step of: providing an extrusion die; heating a first polymer based composition to create a melt; forcing the melt through the extrusion die to form an extruded substrate; providing a roller; guiding the extruded substrate below the roller; providing a supply of decorative laminating film having a lamination substrate that is formed from a second polymer based composition; guiding the decorative laminating film between the roller and the extruded substrate, the roller pressing the decorative laminating film against the extruded substrate to fuse the decorative laminating film with the extruded substrate.